Reject full CouponList during deserialization

Author: jihuayu

hll/include/CouponList-internal.hpp

@@ -99,10 +99,10 @@ CouponList<A>* CouponList<A>::newList(const void* bytes, size_t len, const A& al
   const bool emptyFlag = ((data[hll_constants::FLAGS_BYTE] & hll_constants::EMPTY_FLAG_MASK) ? true : false);
 
   const uint32_t couponCount = data[hll_constants::LIST_COUNT_BYTE];
-  // Reject LIST counts larger than the fixed LIST capacity.
+  // Reject LIST counts at or above the fixed LIST capacity.
   const uint32_t listCapacity = 1u << hll_constants::LG_INIT_LIST_SIZE;
-  if (couponCount > listCapacity) {
-    throw std::invalid_argument("Attempt to deserialize invalid CouponList with couponCount > capacity. Found couponCount: "
+  if (couponCount >= listCapacity) {
+    throw std::invalid_argument("Attempt to deserialize invalid CouponList with couponCount >= capacity. Found couponCount: "
                                 + std::to_string(couponCount)
                                 + ", capacity: " + std::to_string(listCapacity));
   }
@@ -154,10 +154,10 @@ CouponList<A>* CouponList<A>::newList(std::istream& is, const A& allocator) {
   const bool emptyFlag = ((listHeader[hll_constants::FLAGS_BYTE] & hll_constants::EMPTY_FLAG_MASK) ? true : false);
 
   const uint32_t couponCount = listHeader[hll_constants::LIST_COUNT_BYTE];
-  // Reject LIST counts larger than the fixed LIST capacity.
+  // Reject LIST counts at or above the fixed LIST capacity.
   const uint32_t listCapacity = 1u << hll_constants::LG_INIT_LIST_SIZE;
-  if (couponCount > listCapacity) {
-    throw std::invalid_argument("Attempt to deserialize invalid CouponList with couponCount > capacity. Found couponCount: "
+  if (couponCount >= listCapacity) {
+    throw std::invalid_argument("Attempt to deserialize invalid CouponList with couponCount >= capacity. Found couponCount: "
                                 + std::to_string(couponCount)
                                 + ", capacity: " + std::to_string(listCapacity));
   }

hll/test/CouponListTest.cpp

@@ -182,14 +182,16 @@ TEST_CASE("coupon list: check corrupt stream data", "[coupon_list]") {
 }
 
 TEST_CASE("coupon list: rejects malformed coupon count in bytes", "[coupon_list]") {
-  // Reject declared LIST counts beyond the fixed LIST capacity.
+  // Reject declared LIST counts at or beyond the fixed LIST capacity.
   uint8_t lgK = 8;
   hll_sketch sk1(lgK);
   sk1.update(1);
   sk1.update(2);
-  auto sketchBytes = sk1.serialize_compact();
+  const auto validBytes = sk1.serialize_compact();
 
-  const uint8_t malformedCount = 10;
+  const uint8_t listCapacity = static_cast<uint8_t>(1u << hll_constants::LG_INIT_LIST_SIZE);
+  const uint8_t malformedCount = listCapacity;
+  auto sketchBytes = validBytes;
   // Keep the input long enough to validate the declared LIST count.
   const size_t requiredLen = hll_constants::LIST_INT_ARR_START
                              + malformedCount * sizeof(uint32_t);
@@ -212,10 +214,12 @@ TEST_CASE("coupon list: rejects malformed coupon count in stream", "[coupon_list
   hll_sketch sk1(lgK);
   sk1.update(1);
   sk1.update(2);
+
+  const uint8_t listCapacity = static_cast<uint8_t>(1u << hll_constants::LG_INIT_LIST_SIZE);
+  const uint8_t malformedCount = listCapacity;
   std::stringstream ss(std::ios::in | std::ios::out | std::ios::binary);
   sk1.serialize_compact(ss);
 
-  const uint8_t malformedCount = 10;
   const size_t requiredLen = hll_constants::LIST_INT_ARR_START
                              + malformedCount * sizeof(uint32_t);
   // Keep the stream long enough to validate the declared LIST count.